A cylinder printing press is well known. Very briefly, a cylinder is rotated on its axis. A portion of the cylindrical outer surface is adapted to sequentially receive and support a sheet of paper stock, carry the sheet through one rotation of the cylinder, and discharge the sheet prior to receiving a next sheet of paper stock.
A feed mechanism is synchronized with the cylinder rotation to sequentially feed the sheets to the paper receiving portion of the cylinder. Mounted below the cylinder is a sliding platform called a chase. The chase carries dies (formally type set used for printing). As the sheet of paper rotates to the bottom of the cylinder, the chase carries the dies into contact with the paper bearing portion of the cylinder and thus sandwiches the paper sheet between the cylinder and the dies carried by the chase. The linear speed of the chase and the peripheral speed of the cylinder are matched so that the sheet is simply rolled across the dies and the figures or designs of the dies are impressed onto the sheets.
As the sheet completes its pass around the cylinder bottom, the printing operation is completed. The section of the cylinder following the sheet bearing portion of the cylinder is relieved or inset to separate the cylindrical surface from the dies and as the cylinder completes its rotation so as to discharge the old and receive the new sheets, the chase is free to return to the start up position and is readied for printing the new sheet.
The present invention is directed to a converted use of the conventional cylinder printing press. In the prior printing press, the dies were provided with ink and in the printing operation, the designs carried by the dies were printed in ink on the paper stock. In the converted printing press, the dies are heated and hot stamping foil i.e. metal foil laminated onto a carrier film e.g. mylar is placed over the dies. (Hereafter the hot stamping foil is sometimes referred to as a foil bearing ribbon.) The heat from the dies is transferred from the configurations formed on the die to the foil which in turn is pressed onto the paper stock. The metal foil is transferred to the stock creating a metallic image of the die configuration e.g. in gold or silver. An explanation of the converted cylinder press is provided in the commonly assigned patents; U.S. Pat. No. 4,744,294, U.S. Pat. No. 4,627,343 and U.S. Pat. No. 3,316,835.
A problem that is experienced with the converted cylinder press concerns the feeding of the ribbon. The ribbon has to be indexed across the die after each printing operation to position an unused portion of the ribbon over each die figure. Because of the nature of the ribbon material, i.e. it flexes, the ribbon is pulled by a puller roller from a supply roll, the die being positioned between the rolls with the ribbon incrementally and controllably drawn across the dies by the action of the puller roller and its associated control mechanism.
Because of the nature of the control mechanism required for rewinding the used ribbon and for controlling the puller roller action, the various take-up mechanism including a used ribbon (foil) take-up or rewind roller, is mounted in a stationary cabinet at a position rearward from the path of the reciprocating chase and supply roll mounted on the chase. A translation mechanism adjusts the path of the ribbon as the space between the chase and take-up mechanism is varied so as to avoid loosening and tightening of the ribbon as the chase is reciprocated back and forth.
The take-up mechanism of the cylinder press previously available on the market could not adequately control the indexing of the ribbon. Large gaps were provided between the areas of foil transfer in order to avoid the undesired occurrence of overlapping. The foil that was wasted far exceeded 50% of the available foil on the ribbon. Furthermore, the limited number of sheets that could be "printed" per roll of ribbon meant more frequent servicing of the press, i.e. changing of the supply roll. Still further, the stress on the components of the take-up mechanism to attempt a reasonable utilization of the foil caused severe wear problems and undesired frequent repair.